FMC Electrical Violation

[bill1952]

Interesting, same question was just discussed on another board. I commented that of the 100 or so projects I've worked on, I think the EE specified wire grounds. Others pointed out the EMT is electrically better and the EEs specify it because their fee is based on percentage of work (not my experience).

I just wired my new barn/garage - all EMT - and ran a wired ground - so I guess I side with the EEs I've worked with.

With all the things code requires, odd wired grounds in EMT isn't one of them. I suppose it's an incentivize EMT use over less robust systems.

 

[e hilton]

the EEs specify it because their fee is based on percentage of work (not my experience).

My AoR and EoR set their fee based on hours, permit fees, and reimbursables. Never on project value.

 

[jar546]

Granted, EMT can be used as a EGC but how often do you encounter that?

Often. Especially in condo remodels. Most are piped with EMT and ECs doing that type of work don't want to or don't have the skills to bend conduit to move a location so they use FMC. Most of the older condos have EMT as the EGC. Another issue is changing a panel in a high-rise that is flush mounted. Getting all of the pipes to line up with the new panel holes is a bitch. FMC is often used there.

 

[ICE]

Interesting, same question was just discussed on another board.

There was mention of a study that concluded that the efficacy of an EMT EGC deteriorates over time. Of course a study could go either way. My intuition leads me to believe that EMT is not as reliable as wire.

 

[Beniah Naylor]

All of the engineers around specify a wire-type EGC. Whenever I have mentioned using the EMT as the EGC to local electricians, they become alarmed at the very thought, and I feel the need to escape before they burn me for witchery.

I suggest that the reliability of the EMT EGC rests on the fittings used to make the connections. The "SharkBite" style EMT fittings seem to be promising in that regard, as they are harder to install improperly.

https://www.eaton.com/us/en-us/cata...raintight-connectors-and-couplings---emt.html
https://www.southwire.com/simpush

 

[bill1952]

My AoR and EoR set their fee based on hours, permit fees, and reimbursables. Never on project value.

That's my experience. Institutions - public schools, state universities, and similar - do often have published guidelines though, at least for total design fee versus construction cost.

 

[bill1952]

My intuition leads me to believe that EMT is not as reliable as wire.

I lean that way. I wonder if the consequences of not having the wire are really that significant? Do we have a record of any sort of failed EMT ground resulting in losses? Very fine line.

 

[Norcal]

While I prefer a separate grounding conductor, my understanding is a conduit such as EMT is a better EGC.

 

[ICE]

I found this on the internet:

Is there any data on the resistance of a ten-year-old EMT installation with setscrew connectors? I have every confidence in the material, less so in the pesky little details.